A study that provides evidence for the role it plays and explains the significance of this evidence is Hetherington and Ranson, they summarised that rats with lesions to Ventromedial Hypothalamus became overweight. They concluded that destruction of the VH which was responsible for controlling feeding behaviour this then lead to an increase in feeding and body weight. It was then assumed that the rat’s satiety centre was not working correcting which usually indicates when we’re full. At the time of the study it couldn’t be said whether or not the study accurately showed the role of the VN however later studies have had similar outcomes and supported this studies findings.
The hormone that is involved in signalling satiety is Cholecystokinin CCK which is the hormone released due to presence of food and sends signals to the VH to indicate satiety. CCK works when food passes from the duodenum, CCK is then released which signals satiety to the brain.
A study into CCK is Smith, Gibbs & Kulkosky they injected CCK in animals and humans they found that it lead to a decrease in human size it also sends signals of satiety to the brain. Absence of CCK leads to obesity.
A limitation of this study would be ethical issues with the rats well being as the study holds strong forms of animal cruelty.
The part of the brain which receives signals of hunger is the Lateral Hypothalamus it is part of the hypothalamus it functions as a feeding centre, stimulating feeding in response to signals from the body.
Anad and Brobeck is 1951 is a research study which provides evidence for the role the LH plays in satiety. Their findings showed that lesion to the lateral hypothalamus causes aphagia. This means that the rats always felt full, so therefore they did not eat.
The hormone involved in regulating body weight is called Ghrelin it is released from empty stomach and sends signal to lateral hypothalamus to indicate hunger.
Evidence for this is Cummings et al 2004 they found that Ghrelin levels were highest when requesting a meal and fell immediately after eating. Cummings investigated changes in blood Ghrelin over time between meals. 6 pps were allowed to eat lunch then Ghrelin samples were taken every five minutes from a tube inserted into the vein until the pps requested their evening meal. 5 of the 6 pps Ghrelin levels were closely correlated with the degree of hunger reported by the pps. They researchers concluded that Ghrelin levels notify stomach emptiness and are closely related to subjective feelings of hunger.
Limitations of this study is that the data was correlation, so we cannot say that Ghrelin causes feelings of hunger also the all the pps were male therefore there’s problems generalising results to the wider population in general and to females.
The hormone involved in regulating body weight is called Leptin which is released from adipose to indicate body weight and reduce food intake.
